I have a 91 Camry, 4cyl., 113,000 miles. It runs great when it first starts, but soon after it warms up, it runs rough and/or stalls and won't start until it cools down, when it starts and runs like a champ again. I've replaced the fuel filter, distributor cap, spark plugs and wires. Any suggestions? Thanks.

 

I'm not sure what sensors are on a 91. But it sounds like you're running rich when hot. If it's getting too much gas when hot that would explain why it starts and runs ok when cold. Have you tried holding the gas pedal to the floor when it won't start? You could also pull a plug and see if it's gas soaked, that would also tell you it's running rich. If it is running rich I would look for a bad engine coolant temperature switch. If you have a cold start injector then the temp switch may not shut it off when hot. Even a very dirty air filter will cause the car to runrough when hot. Maybe someone more familiar with a 91 can contribute.

 

Thanks-I'll give thoseideas a try.

 

try checking the thermostat.

 

After checking everything I could think of, I threw up my hands and took it to a Toyota mechanic. He asked me what kind of spark plugs I put in (Autolite). He replaced them with Toyota plugs and it runs like a dream. He said he has seen this a few times in older Camrys with Autolite plugs. Food for thought

 

Thanks for the update. Interesting and I wonder why. Course I would never use Autolites, at least in a Camry. I wonder if they were defective or their resistance increasedwhen hot so that the spark was too weak to fire. Mysteries